Wong is the 19-year-old student face of the Umbrella Movement, which brought major Hong Kong roads to a standstill for more than two months last year with protests calling for fully free leadership elections.
Bespectacled and baby-faced, his activism brought him international fame and he has been hailed as among the world's most influential figures by magazines including Time, Fortune and Foreign Policy.
"Capital investment has blinded the eyes of David Cameron," Wong told AFP, referring to the British prime minister.
Wong is expected to join protests featuring Amnesty International, Free Tibet and Chinese, Tibetan and Uighur activists as Xi receives a ceremonial welcome in London today.
He wants Cameron's government to do more to stand up to China over what he sees as an abuse of power in Hong Kong.
"For most Hong Kong citizens, we think UK government should be more active. Our observation is that the UK government is just ignoring Hong Kong for the business deals," Wong said.
The semi-autonomous city was returned to China by Britain in 1997 and is ruled under a "one country, two systems" deal which allows it greater freedoms than seen on the mainland.
But activists fear its high degree of autonomy is being eroded, a concern echoed by Britain's Foreign Affairs Select Committee in a report published in March.
Last year's mass protests in Hong Kong erupted after Beijing said candidates for the city's next leader must be vetted by a loyalist committee ahead of a public vote.
Activists were critical of Britain's failure to speak out against China's plans for the 2017 vote, which they said breached the handover agreement.
